From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-by2nam03on0094.outbound.protection.outlook.com ([104.47.42.94]:9952 "EHLO NAM03-BY2-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S932462AbeA1W36 (ORCPT ); Sun, 28 Jan 2018 17:29:58 -0500 From: Sasha Levin To: "linux-kernel@vger.kernel.org" , "stable@vger.kernel.org" CC: Kevin Cernekee , Pablo Neira Ayuso , Sasha Levin Subject: [PATCH AUTOSEL for 4.4 27/36] netfilter: xt_osf: Add missing permission checks Date: Sun, 28 Jan 2018 22:28:42 +0000 Message-ID: <20180128222815.29479-27-alexander.levin@microsoft.com> References: <20180128222815.29479-1-alexander.levin@microsoft.com> In-Reply-To: <20180128222815.29479-1-alexander.levin@microsoft.com> Content-Language: en-US Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Sender: stable-owner@vger.kernel.org List-ID: From: Kevin Cernekee [ Upstream commit 916a27901de01446bcf57ecca4783f6cff493309 ] The capability check in nfnetlink_rcv() verifies that the caller has CAP_NET_ADMIN in the namespace that "owns" the netlink socket. However, xt_osf_fingers is shared by all net namespaces on the system. An unprivileged user can create user and net namespaces in which he holds CAP_NET_ADMIN to bypass the netlink_net_capable() check: vpnns -- nfnl_osf -f /tmp/pf.os vpnns -- nfnl_osf -f /tmp/pf.os -d These non-root operations successfully modify the systemwide OS fingerprint list. Add new capable() checks so that they can't. Signed-off-by: Kevin Cernekee Signed-off-by: Pablo Neira Ayuso Signed-off-by: Sasha Levin --- net/netfilter/xt_osf.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/net/netfilter/xt_osf.c b/net/netfilter/xt_osf.c index df8801e02a32..7eae0d0af89a 100644 --- a/net/netfilter/xt_osf.c +++ b/net/netfilter/xt_osf.c @@ -19,6 +19,7 @@ #include #include =20 +#include #include #include #include @@ -69,6 +70,9 @@ static int xt_osf_add_callback(struct sock *ctnl, struct = sk_buff *skb, struct xt_osf_finger *kf =3D NULL, *sf; int err =3D 0; =20 + if (!capable(CAP_NET_ADMIN)) + return -EPERM; + if (!osf_attrs[OSF_ATTR_FINGER]) return -EINVAL; =20 @@ -112,6 +116,9 @@ static int xt_osf_remove_callback(struct sock *ctnl, st= ruct sk_buff *skb, struct xt_osf_finger *sf; int err =3D -ENOENT; =20 + if (!capable(CAP_NET_ADMIN)) + return -EPERM; + if (!osf_attrs[OSF_ATTR_FINGER]) return -EINVAL; =20 --=20 2.11.0